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Description

This analytic is designed to detect potentially suspicious batch files that leverage choice.exe as a delay tactic. This technique, observed in the SnakeKeylogger malware, is utilized for time delays or 'Sleep' commands in its code execution or before the deletion of its copies on compromised hosts. Detecting this anomaly serves as a valuable pivot to uncover suspicious processes attempting to evade detection through time-based evasion techniques.

  • Type: Anomaly
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2024-02-14
  • Author: Teoderick Contreras, Splunk
  • ID: d5f54b38-10bf-4b3a-b6fc-85949862ed50

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1497.003 Time Based Evasion Defense Evasion, Discovery
T1497 Virtualization/Sandbox Evasion Defense Evasion, Discovery
Kill Chain Phase
  • Exploitation
NIST
  • DE.AE
CIS20
  • CIS 10
CVE 


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| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.process_name =choice.exe  Processes.process = "*/T*"  Processes.process = "*/N*" by Processes.parent_process_name Processes.process_name Processes.process Processes.process_id Processes.parent_process_id Processes.process_guid Processes.dest Processes.user 
| `drop_dm_object_name(Processes)` 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `windows_time_based_evasion_via_choice_exec_filter`

Macros

The SPL above uses the following Macros:

:information_source: windows_time_based_evasion_via_choice_exec_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required fields

List of fields required to use this analytic.

  • _time
  • Processes.dest
  • Processes.user
  • Processes.parent_process_name
  • Processes.parent_process
  • Processes.process_name
  • Processes.process
  • Processes.process_id
  • Processes.parent_process_id

How To Implement

The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the Processes node of the Endpoint data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process.

Known False Positives

administrator may use choice.exe to allow user to choose from and indexes of choices from a batch script.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
25.0 50 50 A $process_name$ has a choice time delay commandline on $dest$

:information_source: The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

Reference

Test Dataset

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

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